Liquid Cooling System Cold Plate Assembly

ABSTRACT

A cold plate assembly ( 100 ) consisting of a base structure ( 102 ) having a high thermal transfer characteristic, which is adapted for contacting the surface of a heat source ( 10 ) on one side. A fluid transfer component ( 104 ), having a different thermal transfer characteristic is secured to the base ( 102 ) opposite from the heat source receiving side. The fluid transfer component ( 104 ) includes protrusions ( 106 ) adapted for placement into a flow of liquid coolant. A flow of liquid coolant is permitted to pass over the protrusions ( 106 ), but does not contact any portion of the base ( 102 ). Heat is then transferred from the heat source ( 10 ) through the base ( 102 ), into the fluid transfer component ( 104 ), and dissipated into the liquid coolant through the protrusions ( 106 ) which are immersed in the flow of liquid coolant passing through the chamber ( 105 A) via an inlet ( 108 A) and outlet ( 108 B).

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to, and claims priority from, U.S.Provisional Patent Application Ser. No. 60/919,374 filed on Mar. 22,2007, which is herein incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

BACKGROUND OF THE INVENTION

The present invention is related generally to liquid cooling systemsadapted for use in cooling heat sources such as integrated circuitcomponents, processors, and memory modules in a computer system, and inparticular to a cold plate assembly configured for facilitating heatexchange between the heat source and a flow of cooling liquid.

Personal computer systems which are design for desktop or under-deskuse, and which are typically characterized by a main-board ormotherboard housed in a chassis or case, often provide one or moreexpansion slots into which auxiliary components may be installed. Theseauxiliary components may include network adapter circuit boards, modems,specialized adapters, and graphics display adapters. These auxiliarycomponents may receive power through the connection to the motherboard,or through additional connections directly to a system power supplycontained within the chassis or case. Additional components, such ashard drives, disk drives, media readers, etc. may further be containedwithin the chassis or case, and coupled to the system power supply andmotherboard as needed.

During operation, the motherboard and various auxiliary componentsconsume power and generate heat. To ensure proper functionality of thecomputer system, it is necessary to regulate the operating temperaturesinside the environment of the chassis or case. Individual integratedcircuits, especially memory modules and processors, may generatesignificant amounts of heat during operation, resulting in localizedheat sources or hot spots within the chassis environment. The term“processors”, as used herein, and as understood by one of ordinary skillin the art, describes a wide range of components, which may includededicated graphics processing units, microprocessors, microcontrollers,digital signal processors, and general system processors such as thosemanufactured and sold by Intel and AMD. Failure to maintain adequatetemperature control throughout the chassis environment, and atindividual integrated circuits, can significantly degrade the systemperformance and may eventually lead to component failure.

Traditionally, a cooling fan is often associated with the system powersupply, to circulate air throughout the chassis environment, and toexchange the high temperature internal air with cooler external air.However, as personal computer systems include increasing numbers ofindividual components and integrated circuits, and applications becomemore demanding on additional processing components such as graphicsdisplay adapters, a system power supply cooling fan may be inadequate tomaintain the necessary operating temperatures within the chassisenvironment.

Specialized liquid cooling systems are available for some components ina personal computer system. Specialized liquid cooling systems typicallyprovide a liquid coolant circulation pathway, which routes a thermaltransfer liquid between a heat exchanger such as a radiator and one ormore heat source, such as a CPU, GPU, a memory module, a microprocessor,or transformer. At each heat source, the flow of liquid coolant ispassed over a heat transfer component, commonly referred to as a coldplate, which is in contact with the heat source on one side, and theflow of liquid coolant on another side. Typically, a cold plate isconstructed from a metal, such as copper, which has a good ability totransfer heat from the heat source to the liquid coolant. The surface ofthe cold plate in contact with the heat source is generally planar,facilitating a large region of contact, while the surface of the coldplate in contact with the liquid coolant flow may have a number ofprotrusions, fins, or foils extending there from to provide an increasedsurface area for the exchange of heat.

Being composed of metal, the cold plate is generally an expensive andheavy component in any liquid cooling system. For some metals, which areideal heat transfer pathways, the formation of the protrusions, fins, orfoils is difficult or time consuming. For example, to form a cold platefrom copper, with the necessary protrusions to the required tolerances,a complex sintering process is required which is time consuming andexpensive. With other types of metals, such as aluminum, the necessaryprotrusions may be readily formed at a reduced cost by a direct moldingprocess, but lack the heat transfer characteristics of copper. If thetwo different types of metals are utilized in combination, it ispossible that a galvanic corrosion may occur if each metal is in contactwith the liquid coolant, leading to a failure of the liquid coolingsystem, either through corrosion buildup or leakage of the liquidcoolant.

Accordingly, it would be advantageous to provide a cold plate assemblywhich is composed of two or more types of metal, which has a reducedmanufacturing cost, an in which only a single type of metal is incontact with the liquid coolant, reducing the risk of galvaniccorrosion.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, the present disclosure provides a dual-metal cold plateassembly for use with a circulating liquid cooling system. The coldplate assembly consists of a base of first metal having a high thermaltransfer characteristic, which is adapted for contacting the surface ofa heat source on one side. A fluid transfer component, formed from asecond metal, is secured to the base by soldering or welding, oppositefrom the heat source receiving side. The fluid transfer componentincludes numerous protrusions, fins, or pins opposite from the base, andis adapted for placement into a flow of liquid coolant. The cold plateassembly is retained within a housing, such that a flow of liquidcoolant is permitted to pass over the numerous protrusions, fins, orpins of the fluid transfer component, but does not contact any portionof the base. Heat is then transferred from the heat source through thebase, into the fluid transfer component, and dissipated into the liquidcoolant through the various protrusions, fins, and/or pins which areimmersed in the circulating flow of liquid coolant.

In an embodiment of the present invention, the base is formed from asolid copper disk, and the fluid transfer component is formed frommolded aluminum, soldered to the base.

The foregoing features, and advantages set forth in the presentdisclosure as well as presently preferred embodiments will become moreapparent from the reading of the following description in connectionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the accompanying drawings which form part of the specification:

FIG. 1 is a side sectional view of a cold plate assembly of the presentinvention; and

FIG. 2 is a bottom view of the cold plate assembly of FIG. 1.

Corresponding reference numerals indicate corresponding parts throughoutthe several figures of the drawings. It is to be understood that thedrawings are for illustrating the concepts set forth in the presentdisclosure and are not to scale.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The following detailed description illustrates the invention by way ofexample and not by way of limitation. The description enables oneskilled in the art to make and use the present disclosure, and describesseveral embodiments, adaptations, variations, alternatives, and uses ofthe present disclosure, including what is presently believed to be thebest mode of carrying out the present disclosure.

Turning to the Figures, a cold plate assembly 100 of the presentinvention adapted for secured over a heat source 10 such as anintegrated circuit, video or graphic processing unit is shown configuredfor connection to an existing liquid cooling circulating flow loop viaany suitable liquid pathway. Preferably the liquid cooling loop, whichis not directly part of the present invention, provides all necessarycomponents for circulating a flow of liquid coolant to and from the coldplate assembly 100 through inlets 108A and outlets 108B, thereby drawingheat away from the various heat-generating components 10 in proximity tothe cold plate 100.

Preferably, the cold plate assembly 100 is made from materials whichhave a high conductivity to facilitate a transfer of heat, such asmetals like copper or aluminum. The cold plate assembly 100 consistsgenerally of a base structure or high thermal conductivity insert 102, afluid transfer component 104, and a housing 105 which may optionally beintegrally formed with the fluid transfer component 104. The basestructure 102 is adapted for placement in contact with the surface ofthe heat source 10, and preferably consists of a high conductivitymaterial which is adapted for contact with the heat source 10. Heat istransferred from the heat source 10 through the region of highconductivity material 102, such as copper, to the fluid transfercomponent 104. The fluid transfer component 104 is configured totransfer heat from the base structure 102 to a flow of liquid coolantwhich is circulated through a chamber 105A formed by the housing 105.The flow of liquid coolant enters the chamber 105A through one or moreinlets 108A, and exits through one or more discharge outlets 108B.

The fluid transfer component 104 may include a plurality of radiatingfins 106 or other structures extending within the chamber 105A toprovide for an increase in the available surface area over which heatmay be transferred to the flow of liquid coolant passing through thechamber 105A, and to direct the flow of liquid coolant about acircuitous path through the chamber 105A, maximizing heat absorption byliquid coolant.

The cold plate assembly 100 is operatively secured in contact withdifferent types of heat sources 10 such as processors, memory modules,and graphic display cards by utilizing an exchangeable mounting clipstructure or other bolt-on attachment means 110. Preferably theexchangeable mounting clip structure 110 is configured to facilitateattachment of the cold plate assembly 100 in operative proximity to theparticular heat source 10. While the cold plate assembly shown in FIGS.1 and 2 is generally cylindrical, having a circular base profile whenviewed from the bottom, those of ordinary skill in the art willrecognize that the specific shape and dimensions of the cold plateassembly 100, including the shape and dimensions of the base 102, may bevaried depending upon the particular application for which the coldplate assembly 100 is intended to be utilized.

The base structure 102 of the cold plate assembly 100 is preferably amonolithic form of a single metal, such as a copper disk, and may beformed through any conventional manufacturing process to have at leastone surface adapted for heat transfer from a heat source 10. A secondsurface of the base 102 is configured to be operatively bonded to thefluid transfer component 104, which is preferably formed from a secondmetal, such as aluminum. The base structure 102 may be bonded to thefluid transfer component 104 by any suitable bonding means, such assoldering, brazing, or welding.

By forming the fluid transfer component 104 and housing 105 from asecond metal or heat conductive material which is different from themetal forming the base structure 102, the second metal or heatconductive material may be selected based in-part on the ease with whichvarious protrusions, fins, radiator surfaces, or pins 106 may be formedinto a surface of the fluid transfer component 104 for immersion in theflow of liquid coolant within the housing chamber 105A. For example, thesecond metal or heat conductive material may be selected to be aluminum,enabling the fluid transfer component 104, housing 105, and associatedprotrusions, fins, and radiator surfaces 106 to be formed from a moldingor casting process. Since only the surfaces of the fluid transfercomponent 104 and housing 105 are exposed to the liquid coolant flow,the occurrence of galvanic reactions between the base structure 102 andthe fluid transfer component 104 are reduced or eliminated.

As various changes could be made in the above constructions withoutdeparting from the scope of the disclosure, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

1. A cold plate assembly for use with a liquid cooling system,comprising: a base structure of first material having a high thermaltransfer characteristic, said base structure adapted on at least onesurface for contacting a heat source to facilitate a transfer of heatfrom said heat source to said base structure; a fluid transfercomponent, said fluid transfer component formed from a second materialhaving a second thermal transfer characteristic and adapted for partialimmersion in a flow of liquid coolant on a first surface; and whereinsaid fluid transfer component is coupled on a second surface, to asurface of said base structure to facilitate a thermal transfer of heatfrom the heat source, through said base structure and said fluidtransfer component, to said flow of liquid coolant.
 2. The cold plateassembly of claim 1 wherein at least one of said first and secondmaterials is copper.
 3. The cold plate assembly of claim 1 wherein atleast one of said first and second materials is aluminum.
 4. The coldplate assembly of claim 1 wherein said first material is copper, whereinsaid second material is aluminum.
 5. The cold plate assembly of claim 1wherein said base structure is coupled to said fluid transfer componentby at least one of a bonding, welding, soldering, or brazing means. 6.The cold plate assembly of claim 1 wherein said fluid transfer componentis a molded component.
 7. The cold plate assembly of claim 1 whereinsaid fluid transfer component includes a plurality of protrusions onsaid first surface adapted for immersion in said flow of liquid coolant,said plurality of protrusions providing an increased surface area for anexchange of heat between said fluid transfer component and said flow ofliquid coolant.
 8. The cold plate assembly of claim 1 wherein said fluidtransfer component includes a plurality of protrusions on said firstsurface adapted for immersion in said flow of liquid coolant, saidplurality of protrusions directing a flow of liquid coolant within saidfluid transfer component.
 9. The cold plate assembly of claim 1 whereinsaid base structure is isolated from contact with said flow of liquidcoolant by said fluid transfer component.
 10. The cold plate assembly ofclaim 1 further including a housing defining an enclosed chamber oversaid first surface of said fluid transfer component, said housingincluding at least one inlet for receiving a flow of liquid coolant tosaid chamber, and at least one outlet for discharging a flow of liquidcoolant from said chamber.
 11. The cold plate assembly of claim 10wherein said housing is integrally formed with said fluid transfercomponent.